Anyone experienced stuck wipers? Intermittent used to just get stuck occasionally, then kick start itself again and operate correctly, however now intermittent just fails.

Symptoms are that the blade just stops in the most odd positions across the window, and for each wipe will stop in a different position. Often intermittent just stops altogether.

Also, the blade fails to find the park position - and I think this is my clue. I have to time the use of the wiper switch just right!

There are two 'modules' that control the wiper blade N10/2 (which sits in the black box above the fuse box) and the K26 relay module, located just below the blade somewhere.

My suspicion is that the park sensor in the motor assembly is failing such that the module 'thinks' the blade is parked when in fact it isn't OR that the relay driving the motor (K26) has carbon'ed contacts.

There are a few threads about servicing and overhauling the wiper system (not specific to the R129) in the Tech Help forum. I think MBenzNL was the main contributor to it. This is a link to his description of the wiper mechanism on his C250 on his website (I can't imagine the fundamentals are any different).

Managed to get some time last week to strip down the wiper parked sensor (slip rings) attached to the wiper motor. Unfortunately this unit looks typically 'Mercedes clean', however I bent the slip ring contacts such that they press down firmer on the ring, cleaned them and re-greased the whole unit.

Now the wiper has only failed once over a period of four days (in the rain) - but guess that means something still isn't quite right!

The K26 relay module is located adjacent to the ECU box and isn't too difficult to remove. To inspect the relays within, the RTV seal needs breaking - contacts on mine all look excellent!

The sl-600 (94 129) I have has a speed sensitive system when in low or intermitent positions. It stops the wiper when the car is stopped. If your also has this speed sensor, it may be causing the erratic action.

Interesting as this is the next item I will investigate. It's a sealed unit, but only by RTV so it's easy to prize open. I've already had a brief look (there are around 7 relays inside!) and so maybe the contacts of one of the relays are sticking or have carboned..

Thanks, and very interesting. Like a lot here, I hardly ever see rain in the SL. but when I have had to run the wipers, they do odd things. Mostly they want to park on the right side in the middle of the intermediate sweep. So that module is under the cowl cover ?